Honestly the best thing is to just try them all. I was originally dead set on playing a guardian, and really enjoyed it the first BWE and stress test. Then my guild decided to make new characters the next BWE to try different classes. I played a Warrior and fell in love almost right away. It became more cemented after the 3rd BWE and playing all of the other classes for a few hours. I enjoy every weapon combo, even the ranged ones (I hate ranged usually) that warrior offers.

Now I'm probably going to make a Mesmer alt way before I make a guardian. It is really a try it before you become committed sort of thing with this game, you might be very surprised by a class you never thought you would like.

I thought I was content on engineer but then after this last stress test, that went down the drain...

I have the same problem. Honestly, I've loved everything I've tried in the BWE so far.

I'd like to know how people do it, too. I can never find a class I like, only ones I don't. In WoW I had 5 classes at 85 and only 2 below level 70 (Warlock and Druid which I just couldn't get into). I ended up settling for paladin because of their versatility, but I still often went between my warrior and hunter for melee and ranged DPS in addition to my tank/healer paladin. I guess I just like fulfilling every role

Write all the profession names on paper, and put them in a hat and whatever profession you pick you HAVE to play it! Or you could narrow it down to three classes or so that you have experienced that you have enjoyed and pick one of the three out from the hat.

I've always been indecisive, in wow I have every class to 85. I've always had a hard time picking things out, yet there's people who are able to play the same thing over and over even in different games. How do you people do it? Is there anything in particular you look for when selecting such things?

I thought I was content on engineer but then after this last stress test, that went down the drain... I just don't get how people just decide almost instantly what they're going to play. I see a elementalist, and I think it's awesome they can do so many cool spells and blow crap up with aoe. I see a thief and I think it's awesome how they can shadowstep to their target and have abilities to jump over their enemey. I thought turrets were awesome with engineer, but after this last stress test they turned out kind of meh for pvp which I didn't like. But even then there's still many ways to play engineer that I think are awesome.

Everything is awesome! And I hate it! Because it makes it so I can't decide on anything!

My tip: roll an 8-sided die.

If you want to include race as well, roll a 5 or 10-sided die with it.
Yes, 5-sided die exist, they're just not very common.

I don't think anyone has said this yet ... but some more specific advice would be to play them all. After the tutorial -- which takes like 10 minutes -- you can go directly to the Heart of the Mists and play around as a level 80 with all traits, weapons, and abilities. There are also some tough NPCs around that you can practice your skills on ... you can dig in and see exactly what fits your play style best and avoid getting to level 50 and realizing you made a mistake.

FWIW, I was dead set on Mesmer until I did the above and found that the Necro is much more what I am looking for from a main (the necro's abilities seemed so bland on paper but man is it fun!)

What is fun (you can backtrack games you have played and find patterns of what is most fun for you)
What kind of play style the class offers (does it tank well, heal well, ranged/melee dps well, ...)
What are the role playing qualities of the class and how do they match my preferences.

I might have to try the draw from the hat thing. But not include classes I'm simply not interested in, like guardian and warrior. Cool classes, just never been my cup of tea. So that leaves me with Ele, Mesmer, Necro, Thief, Ranger, Engineer... And whatever they add in a later expansion! =P

And as someone mentioned, researching, as much as I love doing it, is what puts me in this state of not being able to choose. Probably just need to dumb it down, and pretend I don't know all the details and base it off of animations and clothing. Too often I'll try to think whats fun in certain situations, like what would be fun in WvW... Well staff elementalist would be pretty cool with all that aoe for mass battles, but then I'm like, but to play one effectively you really have to be constantly attunement swapping which just doesn't sound fun to me. Then I'm like, well, theif would be cool in sPvP, but then I'm like, but it would suck for WvW! Little to no aoe! Bah humbug....
Race isn't really a problem, pretty much set on human or asura.

I've played warrior and paladin in WoW, different game I know, but the general idea is there. I can't stand paladin, and warrior is fun, but I feel like it's too faceroll, and I've heard similar things about it in GW2.

I've played warrior and paladin in WoW, different game I know, but the general idea is there. I can't stand paladin, and warrior is fun, but I feel like it's too faceroll, and I've heard similar things about it in GW2.

Sorry man, but the similarities are pretty sparse. I mean, they do wear plate, and use melee weapons sometimes, but that's about it. Especially the guardian-pally comparison, they are really nothing alike at all.